Polyolefin polymers and more specifically polypropylene and its copolymers and polyethylene and its copolymers are used for the production of electronic parts such as housings, cases and lamps sockets, building construction elements such as roof membranes, wall panels, film and sheets as well as wire and cable insulations in transportation among others. In most of these applications, flame retardancy is needed and is usually provided by flame retardant systems based on a combination of brominated flame retardants with antimony trioxide as a synergist. But this type of flame retardant system has limitations, because antimony trioxide, being a very efficient synergist, tends to significantly increase smoke yield, which impairs visibility which could create problems for evacuation of people in the case of a fire. Further, antimony trioxide has a very high bulk density which increases the specific gravity of molded parts containing the same. This is especially undesirable in transportation and aviation applications. Furthermore, antimony trioxide has significantly increased in price in recent years. Still further, some recently introduced ecolabels require elimination of antimony trioxide from thermoplastic parts.
Although there is a clear need for low antimony trioxide or antimony trioxide-free flame retardant plastics, such plastics usually requires a significant increase in the loading of brominated flame retardant which is also undesirable.